Plastic film sealing blade

ABSTRACT

A plastic film sealing blade is mounted to a side sealing mechanism for cutting and sealing a plastic film moving in a given direction. The sealing blade includes a board body having opposite primary faces and an edge. Slots are defined in the board for fixing the sealing blade to the side sealing mechanism whereby the sealing blade is movable by the side sealing mechanism to a cutting position. The edge forms a V-shaped cutting notch delimited by opposite sharp edge sections, each having an edge line from which an inclined face extends to each primary face of the board to thereby guide and cut a plastic film moving in the given direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the field of side sealing device for plastic packaging films, and in particular to a sealing/cutting blade of the side sealing device that forms a notch having sharp edge sections to facilitate guiding and cutting of the plastic packaging film.

2. The Related Art

Heat-shrinkage films made of plastics are commonly used in packaging goods for purposes of decoration and protection. For example, the plastic film is used to pack such as CDs that are enclosed in plastic cases and books. The plastic film is also used to package food to keep freshness and protect of the packaged food. A plastic film sealing device is employed to package these goods with the plastic film. The plastic film that wraps the goods is often sealed along front, rear, and lateral sides of the packaged goods. Thus, the packaging efficiency and quality is determined by the sealing operation along the sides of the packaged goods and the sealing device used to perform the sealing operation.

A conventional side sealing device, such as that disclosed in U.S. Pat. No. 6,604,340, comprises a flat-board-like sealing blade, which is wholly heated before performing sealing operation. The high temperature of the heated blade melts and thus cuts off the plastic film. The plastic melt is then solidified to form a seal. Due to the facts that plastic film is not always maintained in a straight and tight condition, and that the area of the sealing blade for performing sealing operation on the film is large, non-uniform, skewed and irregular sealing edge is commonly observed in the goods packaged by plastic film by the conventional sealing device. This deteriorates the quality and appearance of the packaged goods.

Thus, it is desired to have a plastic film sealing blade for overcoming the drawbacks encountered in the prior art sealing device.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a plastic film sealing blade having an edge facing coming direction of a plastic film, a notch being formed in the edge to smoothly guide and cut off the plastic film, thereby making straight and smooth sealing edge along the plastic film.

Another objective of the present invention is to provide a plastic film sealing blade having an edge defining a cutting notch that is delimited by sharp edge sections, each forming an inclined face to straighten the plastic film that is cut off and wraps an article.

To achieve the above-mentioned objectives, in accordance with the present invention, a plastic film sealing blade is provided, comprising a board body having opposite primary faces and an edge. Slots are defined in the board for fixing the sealing blade to the side sealing mechanism whereby the sealing blade is movable by the side sealing mechanism to a cutting position. The edge forms a V-shaped cutting notch delimited by opposite sharp edge sections, each having an edge line from which an inclined face extends to each primary face of the board to thereby guide and cut a plastic film moving in the given direction

In accordance with the present invention, the notch and the sharp edge sections delimiting the notch function to guide, flatten, and cut a plastic film and uniformly heating and thus forming a high-quality sealing edge of the plastic film.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent to those skilled in the art by reading the following description of a preferred embodiment thereof, with reference to the attached drawings, in which:

FIG. 1 is a perspective view of a plastic film sealing blade constructed in accordance with the present invention;

FIG. 2 is a side elevational view of the plastic film sealing blade of the present invention;

FIG. 3 is a perspective view of a plastic film side sealing device in which the plastic film sealing blade of the present invention is mounted;

FIG. 4 is also a perspective view of the plastic film side sealing device taken from a different direction;

FIG. 5 is a side elevational view of the plastic film side sealing device; and

FIG. 6 is a side elevational view with an enlarged scale, illustrating the plastic film sealing blade of the present invention guiding and cutting off a plastic film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings and in particular to FIGS. 1 and 2, a sealing blade constructed in accordance with the present invention, generally designated with reference numeral 100, comprises a flat-board-like body having opposite primary surfaces defining a thickness of the boar. A plurality of connecting slots 10 is defined in the blade 100. The slots 10 can be of any desired shaped and are preferably elongated. A cutoff or notch 20 is defined in a front edge of the board. The notch 20 can be of any desired shaped, but is preferably a V-shape as illustrated in the drawings. The V-shaped notch 20 is delimited by two sharp edge sections 21, each edge section having an edge line and opposite inclined faces extending from the edge line to the primary faces of the board respectively. Alternatively, the edge line may be coincident with one of the primary face and the sharp edge section 21 has only one inclined face extending from the edge line to the opposite primary face of the board.

FIGS. 3-5 show a plastic film side sealing mechanism 200 comprising a blade driving device 210. The sealing blade 100 of the present invention is mounted to a support bar 211 of the driving device 210 by means of bolts 11 received in the slots 10 of the sealing blade 100. The sealing blade 100 that is fixed to the support bar 211 is selectively driven by the driving device 210 to move in a vertical direction, as indicated by the arrow shown in FIG. 5. By such a movement, the sealing blade 100 is deposited into and/or retrieved from a sealing chamber 220 of the side sealing mechanism 200.

Also referring to FIG. 6, the side sealing mechanism 200 comprises film feeding device comprised of film guiding members 230 located on opposite sides of the sealing chamber 220 to guide and feed a plastic film 300 in a sideway direction, which in the embodiment illustrated, is substantially normal to the vertical direction, through the sealing chamber 220. Thus, by descending the sealing blade 100 into the sealing chamber 220, the front edge of the sealing blade 100 faces the coming direction of the plastic film 300. The sealing blade 100 is set to have the V-shaped notch 20 substantially corresponding to the plastic film 300 whereby the plastic film 300 is driven by the film guide member 230 directly into the notch 20 and is instantaneously heated and thus cut off by the sharp edge sections 21 of the notch 20. A high-quality, good-looking, and uniform sealing edge along the plastic film 300 can thus be formed.

The inclined edge lines of the edge sections 21 of the V-shaped notch 20 also serves to guide the movement of the plastic film to enhance cutting of the film 300.

Although the present invention has been described with reference to the preferred embodiment thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims. 

1. A plastic film sealing blade comprising a board body having opposite primary faces and an edge, slots being defined in the board for fixing the sealing blade to a side sealing mechanism, the edge defining a cutting notch for guiding and cutting a plastic film moving relative to the sealing blade.
 2. The plastic film sealing blade as claimed in claim 1, wherein the slots defined in the board are elongated.
 3. The plastic film sealing blade as claimed in claim 1, wherein the notch defined in the edge of the board is V-shaped.
 4. The plastic film sealing blade as claimed in claim 1, wherein the notch is delimited by sharp edge sections.
 5. The plastic film sealing blade as claimed in claim 4, wherein each sharp edge section comprising an edge line and an inclined face extending from the edge line to the primary face of the board. 